A railroad trackwork frog assembly is typically inserted in railroad trackwork at the intersection of a mainline rail and a turnout rail to permit the flanges of railcar wheels moving along one of such rails to pass across the other. The frog assembly supports the wheels over tread surface omitted between the frog throat and the frog point, and provides flangeways for aligning the railcar wheels when passing over the frog point so that they will be afforded an adequate load-bearing support area at all times during wheel rail-crossing movement. Generally, standard turnout frogs may be classified as rigid frogs which have no movable parts or movable wing frogs in which one or both of the included wing elements move outward to provide the railcar wheel flangeway or flangeways.
As railcar wheels pass through the frog in either direction, they must pass over the opposite run flangeway from the frog point element to the frog wing element or from the frog wing element to the frog point element depending on the direction of movement. As this occurs, the vertical wheel loadings which the frog is subjected to are increased as a factor of the railcar speed; the resultant impact loadings are transmitted to the frog load-receiving tread surfaces. Such impact loadings, particularly in the case of frogs utilized in mainline heavy duty, high speed trackwork applications, often exceed the yield strength of the typical included railbound frog manganese casting and as a consequence unwanted frog tread surface deterioration begins.
Such deterioration may involve manganese alloy metal flows, metal chipping, and/or metal cracking that develop over a period of time directly related to such factors as traffic frequency, railcar wheel loads, turnout conditions, railcar wheel profiles, track alignment, tie and ballast conditions, initial integrity of the casting metal, adequacy of maintenance, repair materials and practices, and the like. In representative rail trackwork frog service, and depending on the traffic duty, the frog point element and one of the frog wing elements will deteriorate to an unacceptable degree and thereby require maintenance attention. When a frog manganese casting element deteriorates to a condition that is unrepairable, the entire frog assembly must be replaced or in some instances the casting is "changed-out" with the incorporating frog assembly still installed in the track. In either case, the maintenance procedure is costly. If the opposite wing element or the assembly frog point element were in a near-new condition it could be salvaged if it were a separate element.
It is an important object of the present invention to provide a railroad trackage rigid railbound frog assembly which may be utilized in a manner which results in a significant reduction of maintenance repair and replacement costs, and particularly when utilized in railroad trackage applications involving an industry mainline heavy duty, high speed class of traffic.